When can we start reserving seats?

Aloha e Rene,

You do need the actual JR Pass to make seat reservations, so unless you'd have a JR Pass for your husband already, you could not do so right away. The JR East website I linked to you in your other post is an exception to this and would allow you to make reservations but only on JR East trains.

That said, I don't think you have to worry about seating together. Trains rarely sell out on normal days. Only during national holidays should reservations be made a couple days in advance.

Kind regards,
Daniel